FIG. 2 is a block diagram showing an example of a conventional image sensing apparatus having a solid-state image sensing apparatus. In FIG. 2, reference numeral 21 denotes a lens unit; 22, an aperture unit to control the amount of light outputted from the lens unit 21; 23, a CCD solid-state image sensing device (hereinbelow, simply referred to as a “CCD”) having an array of photoelectric transducers, to obtain an image by focusing of light obtained via the lens unit 21 under the control of a CCD driver 28; 24, a camera signal processor to sequentially process a signal outputted from the CCD 23 and convert the signal into a video signal image; 25, a video signal processor to control a display unit 27 provided in the image sensing apparatus and convert a video signal outputted from the camera signal processor 24 to a signal in a format to be displayed on the display unit 27; 26, a system controller to detect an ON/OFF status of a main power switch 29 and control the lens unit 21, the aperture unit 22, the CCD driver 28 and the video signal processor 25 thus control the entire apparatus.
In an apparatus using a solid-state image sensing device, if a defective pixel due to a partial crystal defect of the solid-state image sensing device known as a white flaw is detected, the flaw is compensated with signals outputted from elements of peripheral pixels, as disclosed in Japanese Published Unexamined Patent Application No. 2002-152601. The defective element must be detected by blocking incident light from the lens unit. Next, control performed by the system controller 26 when the white flow detection procedure is performed in the image sensing apparatus shown in FIG. 2 will be described with reference to a flowchart of FIG. 5.
First, the system controller 26 monitors the status of the apparatus power switch 29, and when an apparatus power ON operation has been detected, controls the respective blocks in the apparatus to initial statuses (step S1). Next, the system controller 26 instructs the video signal processor 25 to perform mute setting processing to display a predetermined video raster image or the like in place of an image obtained by image sensing on the display unit 27 (step S2). Next, the system controller 26 controls the aperture unit 22 to completely close, to block incident light from the lens unit 21 (step S3). In this status, the well-known CCD flaw detection processing and determination of adjacent elements to be utilized upon detection of flaw are performed (step S4). Next, the system controller 26 releases the aperture unit 22 (step S5), and starts control by the aperture unit 22 so as to control the amount of light incident on the CCD 23 to an appropriate level (step S6). When the light amount has been controlled to the appropriate level by the aperture unit 22, the system controller 26 controls the video signal processor 25, to release the mute setting with the video raster signal or the like on the display unit 27 and display an image obtained by image sensing formed on the CCD 23 on the display unit 27 (step S7).
As described above, in the image sensing apparatus, upon power-on, the initialization processing and the white flow detection processing on the solid-state image sensing device, and further, processing to determine an aperture amount in an initial stage (hereinbelow referred to as “initial aperture-amount computation processing”) are required. FIG. 3 shows the relation among these processings.
FIG. 3 shows time series apparatus statuses when the power is ON. A period A is time required for initialization of the respective blocks immediately after the apparatus power ON; a period B, time required for the above-described CCD flaw detection and setting of correction upon detection of flaw; and a period C, time required for initial aperture-amount computation to control the amount of incident light from the lens unit 21 via the aperture unit 22 to the CCD 23 to an appropriate level.
The initial aperture-amount computation processing is in exclusive relation with the above-described CCD flaw detection control since the initial aperture-amount computation processing is performed by detecting the amount of incident light from the lens unit 21 by the CCD 23. To maintain high image quality, the CCD flaw detection and correction setting processing are indispensable, accordingly, the time from the apparatus power ON to output of image obtained by image sensing on the display unit is “period A+period B+period C”, which is not negligible.
Note that when the initial aperture-amount computation processing has been completed, as the amount of aperture in the aperture unit 22 in the initial stage is determined, normal AE processing is performed thereafter, then the apparatus enters an image sensing status, and recording is performed in accordance with necessity. However, recording is not performed simultaneously with the start of the AE processing. That is, generally, when the apparatus becomes in an image-sensing possible status, an image is displayed on a display device such as a finder, and the display of a subject image is checked and then a recording button is operated. Accordingly, the initial aperture amount upon start of AE processing, i.e., the initial aperture-amount computation processing is necessary, but high accuracy is not required in the processing.